Mass spectrometry Matrix Assisted Laser Desorption Ionization -TIME OF FLIGHT Used for non volatile sensitive heat labile substances/proteins used to detect and characterize mixture of organic molecules used in quality control MALDI-TOF mass spectrometry is a versatile analytical technique to detect and characterize mixtures of organic molecules. In Microbiology, it is being used as a rapid, accurate and cost-effective method for the identification of microorganism (bacteria, fungi and viruses) Latest efficient technology

1. MALDI-TOF

2. This Photo by Unknown Author is licensed under CC BY
MASS SPECTROMETRY

3. WHAT IS MALDI-TOF?
 Matrix Assisted Laser Desorption Ionization- Time of Flight
 MALDI- Term was coined in 1985 by Franz Hillenkamp and Michael Karas at university of Munster Germany.
 Soft ionization technique
 Non volatile and thermally unstable compounds
 Principle: velocity of ions depend on its mass and energy, the time taken by an ion to travel a specified
distance(TOF).
 Use- MALDI ionization and TOF of ions to reach the detector as a parameter to measure m/z ratio.
 Sample excitation- from the energy of a laser transferred via a UV light absorbing matrix

4. PRINCIPLE
The basic principle associated with
a mass spectrometry encompass
the generation of gas-phase ions
derived from analyte, and the
measurement of mass-to-charge
ratio (m/z).
The time (t) required for the ion to
travel the length of the field-free
region is measured and used to
calculate the m/z of the ion,
The larger the ion, the slower its
velocity and thus the longer it takes
to traverse the field-free drift zone.
Ions
Flight tube
Detector
Acceleration of ions
Ion separation(according to m/z)
TOF
Mass

5. PROCESS
STEP1
•Mix sample and
matrix solutions in
suitable ratio.
STEP 2
Put a some of this
mixture on the target
plate.
Let the mixture co-
crystallize
2018
STEP 3
Insert the target plate in
the MALDI mass
spectrometer (running
under high vacuum).
STEP 4
Shoot with the laser on
the MALDI preparation
to generate ions (singly
charged predominantly).
STEP 5
Collect, analyze and
detect the resulting
ions.
This Photo by Unknown Author is licensed under CC
BY-SA
This Photo by Unknown Author is licensed under CC BY

6. PARTS OF
MALDI-TOF
Sample plate
Matrix
Laser
Variable voltage grid
Vacuum system
Flight tube
Time mass detectors

7. MATRIX
The sample to be analyzed is mixed or coated with
an organic compound that contains an absorbent
solution called matrix.
Commonly used matrixes
• α-cyano-4-hydroxycinnamic acid
• 2, 5-dihydroxybenzoic acid
• 3, 5-dimethoxy-4-hydroxycinnamic acid,
• 2, 6-dihydroxyacetophenone
The matrix compounds with the analyte are
deposited on a target plate which is made up of a
conducting metal

8. LASER
Lasers of both ultraviolet (UV) and
infrared (IR) wavelengths are in use.
UV lasers.
• Nitrogen lasers (λ =337nm)
• Nd: Yag lasers (λ =355nm)
IR lasers
• Er:Yag lasers
• TEA-CO2
This Photo by Unknown Author is licensed under CC BY-SA

10. TOF
•The basic principle of the TOF analyzer
is that it determines the time required by
the ion of different size and charge ratio
that takes to travel the length of the flight
tube.
•The ion starts traveling at the same time
where the small and lighter sized ions
travel faster to the detector than the
larger and heavier one.
•
𝑚
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= 2𝑒𝐸(
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𝑑
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11. DETECTOR

12. DETECTION MODES

14. APPLICATIONS
Biochemistry
Clinical and Environmental Bacteriology
Detection of viruses
Organic chemistry
Medicine

15. ADVANTAGES AND LIMITATIONS
Advantages
 Rapid turnaround time (<10 mins)
 95% accuracy at the species level
 Faster
 Low-cost in supplies and technician processing
time
 Little to no fragmentation
Limitations
 Low analytical sensitivity without prior culture
 The discrimination of phyletically related
microorganisms such as Shigella and
Escherichia coli
 Not a tool suitable to detect a low amount of
bacteria

16. REFRENCES
MALDI-TOF mass spectrometry: an emerging technology
for microbial identification and diagnosis (nih.gov)
MALDI.pdf (berkeley.edu)
MALDI–TOF Mass Spectrometry: Principle, Methodology
and Applications – The Science Notes
MALDI-TOF Mass Spectrometry - Creative Proteomics
(creative-proteomics.com)MALDI-TOF Mass Spectrometry
- Creative Proteomics (creative-proteomics.com)
MALDI-TOF Advantages and Disadvantages
(ukessays.com)
PublishedBookSpringer2016.pdf